The general US population should increase their daily physical activity levels to decrease the rising prevalence of obesity.

objective:To determine what effect diet-induced ~12 kg weight loss in combination with exercise training has on body composition and resting energy expenditure (REE) in premenopausal African-American (AA) and European-American (EA) women. Methods and Procedures: This study was a longitudinal, randomized weight loss clinical intervention, with either aerobic (AT), resistance (RT), or no exercise training (NT). Forty-eight AA and forty-six EA premenopausal overweight (BMI between 27 and 30) women underwent weight loss to a BMI <25. Body composition (densitometry), REE (indirect calorimetry), maximal oxygen uptake (VO 2 max), and muscular strength (isometric elbow flexion) were evaluated when subjects were in energy balance. Results: AA women lost less fat-free mass (FFM, P ≤ 0.05) (47.0 ± 4.6 to 46.9 ± 5.0 kg) than EA women (46.4 ± 4.9 to 45.2 ± 4.6 kg). Regardless of race, RT maintained FFM (P ≤ 0.05) following weight loss (46.9 ± 5.2 to 47.2 ± 5.0 kg) whereas AT (45.4 ± 4.2 to 44.4 ± 4.1 kg) and NT (47.9 ± 4.7 to 46.4 ± 5.1 kg) decreased FFM (P ≤ 0.05). Both AT and NT decreased in REE with weight loss but RT did not. Significant time by group interactions (all P ≤ 0.05) for strength indicated that RT maintained strength and AT did not. Discussion: AA women lost less FFM than EA women during equivalent weight losses. However, following weight loss in both AA and EA, RT conserved FFM, REE, and strength fitness when compared to women who AT or did not train.

African American women had lower aerobic fitness than did white women, independent of differences in lean tissue or AEE. Diminished racial differences in SEE, REE, and TEE after adjustment for trunk lean tissue suggest that low EE in African American women is mediated by low volumes of metabolically active organ mass.

Despite comparable decreases in total and trunk fat, white women lost more IAAT and less SAAT than did black women. Waist circumference was not a suitable surrogate marker for tracking changes in the visceral fat compartment in black women.